Leviathan is an alternate history, steampunk inspired tale of WWI. It centers around Alek, the fictional 15 year old son of Franz Ferdinand, whose murder was the spark that ignited the war. Alek is awoken in the night to find his world has been turned upside down, and he is now hunted by his own country. Meanwhile, Deryn Sharp, a 15 year old English girl who wants to be an airbeast pilot, disguises herself as Dylan Sharp and joins the force, making it onto the famous living ship, Leviathan, quite by accident, just as England is being sucked into the war.Told from these two interwoven standpoints, Leviathan is full of contrast. Deryn and Alek couldn’t come from more different backgrounds or be more different people, and they are played off of each other nicely. What was great (and a brilliant choice on Westerfeld’s part) was that there is a sense of urgency and danger in both storylines, so one never felt more crucial than the other. Alek is on the run for his life, and is beginning to question everything he’s ever known, which could have easily tipped the balance of the story in his favor. But at the same time, Deryn is living among strangers disguised as a boy, always trying to prove herself, and always leary, lest someone find out. There was great tension of different kinds in each storyline, and it was fascinating to watch them begin to come together.Perhaps the most interesting aspect of the book (even more than the engaging characters of Alek and Deryn) was the “technology,” as it were. On one side are the Clankers, Westerfeld’s vision of the Germanic/Austro-Hungarian powers. Their world is one of monstrous machine juggernauts of steampunky goodness. Pitted against them are the Western powers of England, France, etc., whose world is made of fabricated beasts. In this version of history, Darwin not only discovered the idea of genetics, but of DNA, and used it to start the science of gene-splicing and created creatures. The Leviathan itself is a whale/beast/machine hybrid, a massive living dirigible. I must say, I was all for the steampunk nature of this book; it was one of the things that attracted me so strongly to it. But as I read, I found England’s fabricated beasts and the idea of this societal genetic freeforall even more fascinating than the Clanker’s machines. When the narrative shifted to Alek storylines, I found myself anxious to get back to Deryn. Not only do I love “disguised” storylines (like Tamora Pierce’s Song of the Lioness series), but Deryn’s world was captivating and rich. Even in all of the fantastic elements, there was a layer of truth. Nothing was clean-cut and simple. Even in England, there were people who found the idea of fabricated beasts immoral, frightening and repugnant. This rang true to me, and illustrated one of the things I love so much about Scott Westerfeld: even in the midst of his far-fetched, extreme worlds, there is always a solid foundation of reality and truth to ground them. Occasionally, shifting between the two worlds could be jarring, but I think that was part of the point, and added to the story. Either way, both were so fully realized and fascinating that I didn’t want the book to end (and now have to wait like a madwoman for the next installment).